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The LIM homeobox family of transcription factors is involved in many processes during the development of the mammalian central nerves system. L3, also called Lhx8 (L3/Lhx8), is a recently identified member of the LIM homeobox gene family and is selectively expressed in the medial ganglionic eminence (MGE). Our previous study demonstrated that L3/Lhx8-null mice specifically lacked cholinergic neurons in the basal forebrain. In this study, we reduced L3/Lhx8 function in the murine neuroblastoma cell line, Neuro2a (N2a), using L3/ Lhx8-targeted small interfering RNA (siRNA) produced by H1.2 promoter-driven vector. The levels of cholinergic markers per cell were diminished without a reduction in the number of marker-positive cells. Intriguingly, GABAergic marker expression and the number of GABAergic cells were dramatically increased in the differentiating L3/Lhx8-knockdown N2a. These results suggest the possibility that L3/Lhx8 is involved in the determination of transmitter phenotypes (GABAergic or cholinergic cell fate) in a population of neurons during basal forebrain development.

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NGIWYamide is a peptide recently isolated from the sea cucumber Apostichopus japonicus. It sti¡ens the connective tissue of the holothurian body wall. Localization of NGIWYamide was investigated by immunohistochemical staining with antiserum raised against NGIWYamide. In holothurian nervous systems NGIWYamide-like immunoreactivity (NGIWYa-LI) was observed in the hyponeural and ectoneural regions of the radial nerve cord, as well as in the circumoral nerve ring, podial nerves, tentacular nerves, the basiepithelial nerve plexus of the intestine and in cellular processes running through the body wall dermis. Labelled nerve ¢bres from the hyponeural part of the radial nerve running towards the circular muscle and from the podial nerve into the body wall dermis suggest that NGIWYamide controls both muscle and connective tissue. We examined the e¡ect on muscle activity of the sea cucumber. NGIWYamide (10 77 to 10 74 M) caused contraction of the longitudinal body wall muscle. Tentacles showed contraction only at a higher dose (10 74 M). NGIWYamide (10 74 M) inhibited spontaneous contraction of the intestine.

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